The present invention relates to an assembly for guiding an inflatable curtain-type airbag cushion across a side portion of a vehicle during a collision event and thereafter holding the airbag cushion in a tensioned condition subsequent to the deployment.
It is well known in motor vehicles to provide air bag cushions for protecting a vehicle occupant during a collision event wherein such air bag cushions are in fluid communication with gas generating inflators so as to inflate the cushions upon sensing predetermined vehicle conditions such as deceleration exceeding a certain level. It is further known to provide air bag systems including inflatable restraint cushions which are deployed from positions of attachment along the roof rail portion of the vehicle frame above the doors of the vehicle such that the inflatable cushion extends downwardly in substantially curtain-like fashion between the occupant to be protected and the side portions of the vehicle adjacent to such occupants. Such coverage provides a cushioning restraint to the occupant during a side impact or extended roll-over collision event thereby aiding in the protection of the occupant during such events.
It is generally desirable for a curtain-like side air bag cushion to be held in a substantially tensioned condition across the surface being covered so as to provide a well defined extended barrier between the occupant and the side portion of the vehicle. Such a condition may be useful in holding the vehicle occupant within the protective frame of the vehicle during an extended roll-over event.
A typical prior tethering arrangement for maintaining tension across the lower edge of a curtain-like cushion is illustrated in FIGS. 1A and 1B. As illustrated, in such prior embodiments an inflatable curtain 10 is stored in packed relation generally along the roof rail 12 of a vehicle 14 generally above the doors 16. The length of the inflatable curtain 10 is such that upon inflation coverage is provided over at least a portion of the distance extending along the side of the vehicle interior between two or more structural pillars 20 extending away from the roof rail 12.
In the illustrated embodiment, the inflatable curtain 10 is shown to be attached at the forward xe2x80x9cAxe2x80x9d pillar and at the rearward xe2x80x9cCxe2x80x9d pillar so as to cover the intermediate xe2x80x9cBxe2x80x9d pillar. As shown, in prior constructions the inflatable curtain 10 is inflated by a gas generating inflator 22 thereby causing the lower edge of the inflatable curtain 10 to move downwardly away from the roof rail 12. As the inflatable curtain 10 undergoes inflation, it tends to shorten as cushioning depth is developed (FIG. 1B). This shortening may be restricted by the presence of tethering straps 24 of fixed length extending between the lower edge of the inflatable curtain 10 and the forward and rearward pillars 20 bordering the area to be covered.
Utilizing the prior design of fixed length tethers 24 is useful in providing tension across the lower edge once the designed inflation of the inflatable curtain 10 is complete provided that the length of the tethers is well matched to the particular coverage characteristics of the inflatable curtain 10 relative to the pillars 20. In particular, once the curtain 10 is in the fully inflated condition if the tethers are of the proper length, a balanced tension is established and may thereafter be maintained between the shortened inflatable curtain 10 and the fully extended tethering straps 24. Thus prior curtain constructions which utilize a combination of inflation induced shortening and fixed length tethering straps 24 are typically dependent upon the cushion shape being substantially fully established before the final tension is generated. Accordingly, the tethers in such systems are generally slack during the preliminary stages of deployment prior to the bottom edge becoming positioned and fully tensioned. After deployment has taken place, the tensioning may be at least partially lost if the airbag cushion becomes deflated.
This invention provides advantages and alternatives over the prior art by providing a system which assists in guiding an inflatable curtain-style air bag cushion into position and which thereafter holds the airbag cushion in place to provide tensioning support to the cushion.
In the invention, a dynamic tethering element is utilized which travels in conjunction with the downward deployment of the inflatable curtain structure so as to both tension the curtain structure while at the same time providing a guiding action so as to bring the curtain structure into the proper position at which it is thereafter maintained. The dynamic tethering element is blocked against retreating movement after deployment has taken place. The dynamic tethering element avoids substantial reliance upon curtain shortening to provide a tensioning force across the inflatable curtain structure. In addition, the dynamic tethering element may be useful in pulling the inflating curtain into a desired position at an early stage of deployment. Accordingly, a number of useful advantages are provided.